A politician says investigators poring over photos and videos from the Boston Marathon bombing have an image of a man dropping off a bag containing one of the bombs.

DENISE LAVOIE and EILEEN SULLIVAN - Associated Press

Updated at 5:45 p.m.

BOSTON (AP) — A politician says investigators poring over photos and videos from the Boston Marathon bombing have an image of a man dropping off a bag containing one of the bombs.

City Council President Stephen Murphy said Wednesday investigators saw the image on surveillance footage they got from a nearby department store. He says he doesn't know if investigators have identified the man.

Murphy says police officers involved in the probe say investigators have matched information from the surveillance footage with witness descriptions of someone leaving the scene.

Murphy says officers are chasing leads that could take them to the man. He says developing that information within the first 48 hours of the probe is a major breakthrough.

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Updated at 4:51 p.m.

BOSTON (AP) — Investigators poring over photos and video from the Boston Marathon have an image of a potential suspect in the deadly bombing but do not know his name and have not questioned him, a law enforcement official said Wednesday.

The news came with Boston in a state of high excitement over a possible breakthrough in the case and conflicting information over whether a suspect was in custody. Police and reporters converged on the federal courthouse in the afternoon.

Several news organizations reported earlier in the day that a suspect had been identified from surveillance video taken at a department store midway between the sites of Monday's two bomb blasts, which killed three people and wounded more than 170.

A law enforcement official who spoke to The Associated Press on condition of anonymity and was not authorized to discuss the case publicly confirmed only that investigators had an image of a potential suspect and had not established his identity.

Also Wednesday, a law enforcement official briefed on the investigation told the AP that a suspect was in custody. The official, who was not authorized to divulge details of the investigation, said the suspect was expected in federal court.

But the FBI and the U.S. attorney's office in Boston said no arrests had been made.

"Contrary to widespread reporting, there have been no arrests made in connection with the Boston Marathon attack," the FBI said in a statement. "Over the past day and a half, there have been a number of press reports based on information from unofficial sources that has been inaccurate. Since these stories often have unintended consequences, we ask the media, particularly at this early stage of the investigation, to exercise caution and attempt to verify information through appropriate official channels before reporting."

The official who spoke to the AP about someone being taken into custody stood by the information even after it was disputed.

A bomb threat forced the evacuation of the courthouse in midafternoon, the U.S. Marshals Service said, and security officials were sweeping the area. Workers were allowed back into the courthouse a short time later.

Law enforcement agencies have pleaded for the public to come forward with photos, videos or any information that might help them solve the case. Police also gathered surveillance video from businesses.

Multiple news organizations, citing unidentified sources, reported Wednesday that a video surveillance camera at a Lord & Taylor department store showed a suspect with a backpack near the finish line.

Investigators have said they believe the bombs were fashioned out of ordinary kitchen pressure cookers packed with explosives, nails, ball bearings and metal shards. They suspect the bombs were hidden in duffel bags and left on the ground.

The bombs exploded 10 or more seconds apart, tearing off limbs and spattering streets with blood.

Scores of victims remained hospitalized, many with grievous injuries. Fourteen were listed in critical condition. Doctors who treated the wounded corroborated reports that the bombs were packed with shrapnel.

The trauma surgery chief at Boston Medical Center said most of the injuries his hospital treated were to the legs.

"We have a lot of lower extremity injuries, so I think the damage was low to the ground and wasn't up," Dr. Peter Burke said. "The patients who do have head injuries were blown into things or were hit by fragments that went up."

The blasts killed 8-year-old Martin Richard of Boston and 29-year-old Krystle Campbell of Medford. The Shenyang Evening News, a state-run Chinese newspaper, identified the third victim as Lu Lingzi. She was a graduate student at Boston University.

BOSTON (AP) — Police and reporters converged on the federal courthouse in Boston on Wednesday amid conflicting reports of whether a suspect was in custody in the marathon bombings that killed three people and wounded more than 170.

Several media outlets reported earlier in the day that a suspect had been identified from surveillance video taken at a Lord & Taylor store between the sites of the two bomb blasts.

A law enforcement official briefed on the investigation told The Associated Press that a suspect was in custody. The official, who was not authorized to divulge details of the investigation, said the suspect was expected in federal court.

But FBI and the U.S. attorney's office in Boston said no arrests had been made.

"Contrary to widespread reporting, there have been no arrests made in connection with the Boston Marathon attack," the FBI said in a statement. "Over the past day and a half, there have been a number of press reports based on information from unofficial sources that has been inaccurate. Since these stories often have unintended consequences, we ask the media, particularly at this early stage of the investigation, to exercise caution and attempt to verify information through appropriate official channels before reporting."

The official who spoke to the AP did so on condition of anonymity and stood by the information even after it was disputed. A news briefing was scheduled later Wednesday.

Law enforcement agencies had earlier pleaded for the public to come forward with photos, videos or any information that might help them solve the twin bombings. Police also gathered surveillance video from businesses around the finish line.

The bombs were made from ordinary kitchen pressure cookers packed with explosives, nails and ball bearings to inflict maximum carnage, investigators and others close to the case said. But the FBI said nobody had claimed responsibility.

Investigators in white jumpsuits had fanned out across the streets, rooftops and awnings around the blast site in search of clues on Wednesday. They combed through debris amid the toppled orange sports drink dispensers, trash cans and sleeves of plastic cups strewn across the street at the marathon's finish line.

President Barack Obama branded the attack an act of terrorism. Obama plans to attend an interfaith service Thursday in the victims' honor in Boston.

Scores of victims of the Boston bombing remained in hospitals, many with grievous injuries. Doctors who treated the wounded corroborated reports that the bombs were packed with shrapnel intended to cause mayhem. In addition to the 5-year-old child, a 9-year-old girl and 10-year-old boy were among 17 victims listed in critical condition.

The trauma surgery chief at Boston Medical Center says most of the injuries his hospital treated after the marathon bombings were to the legs.

"We have a lot of lower extremity injuries, so I think the damage was low to the ground and wasn't up," Dr. Peter Burke said. "The patients who do have head injuries were blown into things or were hit by fragments that went up."

Dozens of patients have been released from hospitals around the Boston area.

At Massachusetts General Hospital, all four amputations performed there were above the knee, with no hope of saving more of the legs, said Dr. George Velmahos, chief of trauma surgery.

"It wasn't a hard decision to make," he said Tuesday. "We just completed the ugly job that the bomb did."

The bombs exploded 10 or more seconds apart, tearing off victims' limbs and spattering streets with blood. The blasts near the finish line instantly turned the festive race into a hellish scene of confusion, horror and heroics.

The blasts killed 8-year-old Martin Richard, of Boston, and 29-year-old Krystle Campbell, of Medford. The Shenyang Evening News, a state-run Chinese newspaper, identified the third victim as Lu Lingzi. She was a graduate student at Boston University.

BOSTON (AP) — Federal officials are denying that a suspect is in custody in the Boston Marathon bombings.

A law enforcement official briefed on the investigation told The Associated Press on Wednesday a suspect was in custody.

But the FBI and the U.S. attorney's office in Boston dispute that.

The official who spoke to The Associated Press did so on condition of anonymity and stood by the information even after it was disputed.

The official was not authorized to divulge details of the investigation. The official had said the suspect was expected in federal court in Boston.

Reporters and police have converged at the courthouse.

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Updated at 2:31 p.m.

BOSTON (AP) — A suspect in the Boston Marathon bombings was taken into custody Wednesday in a breakthrough that came less than 48 hours after the deadly attack, a law enforcement official briefed on the investigation said Wednesday.

The official spoke shortly after several media outlets reported that a suspect had been identified from surveillance video taken at a Lord & Taylor store between the sites of the two bomb blasts, which killed three people and wounded more than 170.

The official was not authorized to divulge details of the investigation and spoke to The Associated Press on condition of anonymity. The suspect was expected at a Boston courthouse under heavy security, the official said.

A news briefing was scheduled later Wednesday.

Law enforcement agencies had earlier pleaded for the public to come forward with photos, videos or any information that might help them solve the twin bombings. Police also gathered surveillance video from businesses around the finish line.

The bombs were made from ordinary kitchen pressure cookers packed with explosives, nails and ball bearings to inflict maximum carnage, investigators and others close to the case said. But the FBI said nobody had claimed responsibility.

Investigators in white jumpsuits had fanned out across the streets, rooftops and awnings around the blast site in search of clues on Wednesday. They combed through debris amid the toppled orange sports drink dispensers, trash cans and sleeves of plastic cups strewn across the street at the marathon's finish line.

President Barack Obama branded the attack an act of terrorism. Obama plans to attend an interfaith service Thursday in the victims' honor in Boston.

Scores of victims of the Boston bombing remained in hospitals, many with grievous injuries. Doctors who treated the wounded corroborated reports that the bombs were packed with shrapnel intended to cause mayhem. In addition to the 5-year-old child, a 9-year-old girl and 10-year-old boy were among 17 victims listed in critical condition.

The trauma surgery chief at Boston Medical Center says most of the injuries his hospital treated after the marathon bombings were to the legs.

"We have a lot of lower extremity injuries, so I think the damage was low to the ground and wasn't up," Dr. Peter Burke said. "The patients who do have head injuries were blown into things or were hit by fragments that went up."

Dozens of patients have been released from hospitals around the Boston area.

At Massachusetts General Hospital, all four amputations performed there were above the knee, with no hope of saving more of the legs, said Dr. George Velmahos, chief of trauma surgery.

"It wasn't a hard decision to make," he said Tuesday. "We just completed the ugly job that the bomb did."

The bombs exploded 10 or more seconds apart, tearing off victims' limbs and spattering streets with blood. The blasts near the finish line instantly turned the festive race into a hellish scene of confusion, horror and heroics.

The blasts killed 8-year-old Martin Richard, of Boston, and 29-year-old Krystle Campbell, of Medford. The Shenyang Evening News, a state-run Chinese newspaper, identified the third victim as Lu Lingzi. She was a graduate student at Boston University.

BOSTON (AP) — A law enforcement official briefed on the investigation says a suspect has been taken into custody in the Boston Marathon bombings.

The official spoke to The Associated Press on condition of anonymity Wednesday. The official was not authorized to divulge details of the investigation.

The official says the suspect is expected in federal court in Boston.

Law enforcement agencies had earlier pleaded for the public to come forward with photos, videos or any information that might help them solve the twin bombings that killed three people and wounded more than 170 on Monday.

Investigators circulated information about the bombs, which involved kitchen pressure cookers packed with explosives, nails and other lethal shrapnel. But the FBI said nobody had claimed responsibility.

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Updated at 2:01 p.m.

BOSTON (AP) — A law enforcement official briefed on the investigation says a suspect in the Boston Marathon bombings is about to be arrested.

The official spoke to The Associated Press on condition of anonymity Wednesday. The official was not authorized to divulge details of the investigation.

The official says the suspect is to be taken into custody by federal marshals and taken to a Boston courthouse.

Law enforcement agencies had earlier pleaded for the public to come forward with photos, videos or any information that might help them solve the twin bombings that killed three people and wounded more than 170 on Monday.

Investigators circulated information about the bombs, which involved kitchen pressure cookers packed with explosives, nails and other lethal shrapnel. But the FBI said nobody had claimed responsibility.

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BOSTON (AP) — Authorities investigating the deadly bombings at the Boston Marathon have recovered a piece of circuit board that they believe was part of one of the explosive devices, and also found the lid of a pressure cooker that apparently was catapulted onto the roof of a nearby building, an official said Wednesday.

A law enforcement official briefed on the investigation confirmed to The Associated Press that authorities have recovered what they believe are some of the pieces of the explosive devices. The official spoke on condition of anonymity because this person was not authorized to publicly discuss evidence in the ongoing investigation.

A person close to the investigation previously told AP the bombs consisted of explosives put in 1.6-gallon pressure cookers, one with shards of metal and ball bearings, the other with nails.

Also Wednesday, a doctor at Boston Medical Center said two patients, including a 5-year-old child, remain in critical condition there. Dozens of others have been released from hospitals around Boston.

Law enforcement agencies pleaded Tuesday for the public to come forward with photos, videos or any information that might help them solve the twin bombings that killed three people and wounded more than 170 a day earlier. Investigators circulated information about the bombs, which involved kitchen pressure cookers packed with explosives, nails and other lethal shrapnel — but the FBI said nobody had claimed responsibility.

"Someone knows who did this," Richard DesLauriers, FBI agent in charge in Boston, said at a news conference where he detailed the type of clues a bomber might have left. "Importantly, the person who did this is someone's friend, neighbor, co-worker or relative."

President Barack Obama branded the attack an act of terrorism but said officials don't know "whether it was planned and executed by a terrorist organization, foreign or domestic, or was the act of a malevolent individual." Obama plans to attend an interfaith service Thursday in the victims' honor in Boston.

Scores of victims of the Boston bombing remained in hospitals, many with grievous injuries. Doctors who treated the wounded corroborated reports that the bombs were packed with shrapnel intended to cause mayhem. In addition to the 5-year-old child, a 9-year-old girl and 10-year-old boy were among 17 victims listed in critical condition.

An intelligence bulletin issued to law enforcement includes a picture of a mangled pressure cooker and a torn black bag that the FBI said were part of a bomb that exploded during the marathon.

DesLauriers said cooperation from the community will play a key role in the investigation. He said the range of suspects remained wide open, but by midday Tuesday more than 2,000 tips had been received.

The bombs exploded 10 or more seconds apart, tearing off victims' limbs and spattering streets with blood. The blasts near the finish line instantly turned the festive race into a hellish scene of confusion, horror and heroics.

The blasts killed 8-year-old Martin Richard, of Boston, and 29-year-old Krystle Campbell, of Medford. The Shenyang Evening News, a state-run Chinese newspaper, identified the third victim as Lu Lingzi. She was a graduate student at Boston University.

Officials found that the bombs in Boston consisted of explosives put in ordinary, 1.6-gallon pressure cookers, one with shards of metal and ball bearings, the other with nails, according to a person close to the investigation who spoke on condition of anonymity because the probe was still going on.

Both bombs were stuffed into black bags and left on the ground, the person said.

At Massachusetts General Hospital, all four amputations performed there were above the knee, with no hope of saving more of the legs, said Dr. George Velmahos, chief of trauma surgery.

"It wasn't a hard decision to make," he said. "We just completed the ugly job that the bomb did."

DesLauriers confirmed that investigators had found pieces of black nylon from a bag or backpack and fragments of BBs and nails, possibly contained in a pressure cooker. He said the items were sent to the FBI laboratory at Quantico, Va., for analysis.

Pressure-cooker explosives have been used in international terrorism, and have been recommended for lone-wolf operatives by al-Qaida's branch in Yemen.

But information on how to make the bombs is readily found online, and U.S. officials said Americans should not rush to judgment in linking the attack to overseas terrorists.

Pressure-cooker explosives have been used in Afghanistan, India, Nepal and Pakistan, according to a July 2010 intelligence report by the FBI and the Homeland Security Department. One of the three devices used in the May 2010 Times Square attempted bombing was a pressure cooker, the report said.

"Placed carefully, such devices provide little or no indication of an impending attack," the report said.

Investigators in the Boston bombing were combing surveillance tapes from businesses around the finish line and asking travelers at Logan Airport to share any photos or video that might help.

"This is probably one of the most photographed areas in the country yesterday," said Boston Police Commissioner Edward Davis. He said two security sweeps of the marathon route had been conducted before the blasts.